Principles of lipidomic analysis

Efficient separation of the lipids are achieved using ultra performance liquid chromatography. The overall lipid structures will influence how the different lipids will be separated during the analysis. An example of a chomatographbic analysis separating the different types of lipids in a blood plasma sample is shown in the figure below.

Figure: A representative chromatogram of the separation of a selection of different lipid classes from blood plasma sample using UPLC coupled to high resolution mass spectrometry.

An additional dimension of separation is introduced as the effluent enters into a high-resolution mass spectrometric detector (TOF-MS). The efficient separation allow us to distinguish between lipids of different molecular weights that have identical retention time (first dimension). High and efficient separation is crucial to be able to analyse the great diversity of lipids present in biological samples such as in plasma, serum, saliva, tissues etc. The two-dimensional separation is illustrated in the figure below.

Figure: Illustration of the resolution obtained in 2 dimensions. First dimesion: chromatographic separation in time. Second dimenstion: separation as mass-to-charge ratio using high resolution mass spectrometric detection.